I will specify their names, &c., towards
the close of this chapter, so as not to interrupt my present remarks.
The answers relate to several of the most distinct and savage races of man.
In many instances, the circumstances have been recorded under which
each expression was observed, and the expression itself described.
In such cases, much confidence may be placed in the answers. When the answers
have been simply yes or no, I have always received them with caution.
It follows, from the information thus acquired, that the same state
of mind is expressed throughout the world with remarkable uniformity;
and this fact is in itself interesting as evidence of the close similarity
in bodily structure and mental disposition of all the races, of mankind.

Sixthly, and lastly, I have attended. as closely as I could,
to the expression of the several passions in some of the
commoner animals; and this I believe to be of paramount importance,
not of course for deciding how far in man certain expressions
are characteristic of certain states of mind, but as affording
the safest basis for generalisation on the causes, or origin,
of the various movements of Expression. In observing animals,
we are not so likely to be biassed by our imagination;
and we may feel safe that their expressions are not conventional.

From the reasons above assigned, namely, the fleeting nature
of some expressions (the changes in the features being often
extremely slight); our sympathy being easily aroused when we
behold any strong emotion, and our attention thus distracted;
our imagination deceiving us, from knowing in a vague manner
what to expect, though certainly few of us know what the exact
changes in the countenance are; and lastly, even our long
familiarity with the subject,--from all these causes combined,
the observation of Expression is by no means easy, as many persons,
whom I have asked to observe certain points, have soon discovered.
Hence it is difficult to determine, with certainty,
what are the movements of the features and of the body,
which commonly characterize certain states of the mind.
Nevertheless, some of the doubts and difficulties have,
as I hope, been cleared away by the observation of infants,--
of the insane,--of the different races of man,--of works of art,--
and lastly, of the facial muscles under the action of galvanism,
as effected by Dr. Duchenne.

But there remains the much greater difficulty of understanding
the cause or origin of the several expressions, and of judging whether
any theoretical explanation is trustworthy. Besides, judging as
well as we can by our reason, without the aid of any rules,
which of two or more explanations is the most satisfactory, or are
quite unsatisfactory, I see only one way of testing our conclusions.
This is to observe whether the same principle by which one expression can,
as it appears, be explained, is applicable in other allied cases;
and especially, whether the same general principles can be applied
with satisfactory results, both to man and the lower animals.
This latter method, I am inclined to think, is the most serviceable of all.
The difficulty of judging of the truth of any theoretical explanation,
and of testing it by some distinct line of investigation, is the great
drawback to that interest which the study seems well fitted to excite.

Finally, with respect to my own observations, I may state that they
were commenced in the year 1838; and from that time to the present day,
I have occasionally attended to the subject. At the above date,
I was already inclined to believe in the principle of evolution,
or of the derivation of species from other and lower forms.
Consequently, when I read Sir C. Bell's great work, his view,
that man had been created with certain muscles specially adapted
for the expression of his feelings, struck me as unsatisfactory.
It seemed probable that the habit of expressing our feelings
by certain movements, though now rendered innate, had been
in some manner gradually acquired. But to discover how such
habits had been acquired was perplexing in no small degree.
The whole subject had to be viewed under a new aspect,
and each expression demanded a rational explanation.
This belief led me to attempt the present work, however imperfectly
it may have been executed.--------

I will now give the names of the gentlemen to whom, as I have said,
I am deeply indebted for information in regard to the expressions
exhibited by various races of man, and I will specify some
of the circumstances under which the observations were in each
case made.